This invention relates to a fax/telephone switching device, especially to a device which utilizes a peripheral circuit loop of a fax machine to act as a telephone loop, so that a telephone set of the fax machine can also be used just like a normal telephone to communicate with another telephone.
Heretofore, many kinds of fax machines with an accessory telephonee set to dial the fax numbers of other facsimile stations have been developed in various parts of the world. Many conventional fax machines have an automatic-operation mode in which the fax machine has the so-called "auto-off hook function" (i.e., the fax machine can automatically change from on-hook state to off-hook state without picking up the hook) and a manual-operation mode in which there is no auto-off hook function and the fax machine can only become off-hook when the hook of the accessory telephone is taken up. Since a telephone only rings in its on-hook state, if the automatic-operation mode, the period of calling is transient and it is not long enough to attract the user's attention to pick up the hook. Therefore, the accessory telephone of the fax machine cannot be used as a normal telephone line during the transmission of fax data.
The switching device of this invention is created for providing a general fax machine with additional function--voice or sound communication; i.e., the switching means can identify whether or not the calling signal is a fax transmission or a voice communication. The switching device connects with a fax machine and a telephone and shares a peripheral circuit loop with the fax machine. When the fax machine receives a calling signal, a detector of the switching device detects if the calling signal is fax transmission or voice communications, then the switching device will switch the corresponding elements.